Problem: $\dfrac{5}{12} - \dfrac{4}{8} = {?}$
Answer: $ = {\dfrac{5 \times 2}{12 \times 2}} - {\dfrac{4 \times 3}{8 \times 3}} $ $ = {\dfrac{10}{24}} - {\dfrac{12}{24}} $ $ = \dfrac{{10} - {12}}{24} $ $ = -\dfrac{2}{24}$